Project Synopsis

Provide design changes to improve operations of a methanol drying column in a waterless biodiesel production facility.

Project Summary

BIODIESEL PLANT METHANOL DRYING COLUMN DESIGN

Process Engineering Associates, LLC (PROCESS) was subcontracted by the client, an engineering and construction company, to provide process design and engineering services for a waterless biodiesel production facility. The ultimate client was experiencing difficulties with the methanol drying column operation. Specifically, PROCESS was contracted to perform the following tasks:

Size restriction orifices to be installed in the methanol drying column feed to prevent flashing in the feed heaters

Design a replacement methanol drying column

The existing methanol drying column does not consistently meet product specifications. Part of the problem is feed flashing in the feed preheaters. This limits the ability to consistently heat the feed. A new column design was also desired to allow the ultimate client to purchase new units for other planned plant sites. The existing column was purchased from a technology supplier who did not disclose the original design information or internals configuration. The purpose of the new column design was to generate this information so additional units can be fabricated.

PROCESS used its licensed commercial computer process simulation software, CHEMCAD, to develop a model for the column, its feed heater train, and its vacuum pump and condenser train based on operating data provided by the client. The resulting design information was then used to size the restriction orifices and to supply data for packing selection and column sizing. The restriction orifice sizing was complicated by the fact that the orifice could not be mounted on the column feed nozzle. The calculations had to account for two-phase flashing flow downstream of the orifice.

Data from the simulation were also used to create an equipment duty specification for the column and its internals.